Previously, modules would explicitly disable instrumentation when
ever Darshan core called into the module to shut it down. The
issue is that Darshan core starts shutting down well before modules
do, so there is a time interval where modules could be trying to
instrument data while its not safe to do so.

Now, we expose a function (darshan_core_disabled_instrumentation)
that modules can call to determine if its safe to instrument
data.

Address Darshan-parser  seg fault issue and print OST obdidx in one line

See merge request !11

* mpi-io-test case now also checks that the DXT parser can handle
  a log file with no DXT data
* a new mpi-io-test was added to run with DXT tracing enabled
  to ensure DXT and it's parser are both functioning properly

Signed-off-by: CongXu <cong.xu@intel.com>

disable mmap wrapper for dynamic linking

Closes #223

See merge request !10

see #223

Issue 219 dxt mem config

See merge request !9

this allows us to request memory allocations at smaller granularity
than MiB